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Mechanical and morphological properties of trabecular bone samples obtained from third metacarpal bones of cadavers of horses with a bone fragility syndrome and horses unaffected by that syndrome

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  • 1 Biomedical Engineering Graduate Group, University of California-Davis, Davis, CA 95616.
  • | 2 J. D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.
  • | 3 J. D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.
  • | 4 J. D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.
  • | 5 J. D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.
  • | 6 Biomedical Engineering Graduate Group, University of California-Davis, Davis, CA 95616.
  • | 7 Department of Orthopaedic Surgery, School of Medicine, University of California-Davis, Davis, CA 95616.
  • | 8 Biomedical Engineering Graduate Group, University of California-Davis, Davis, CA 95616.
  • | 9 Department of Orthopaedic Surgery, School of Medicine, University of California-Davis, Davis, CA 95616.
  • | 10 Biomedical Engineering Graduate Group, University of California-Davis, Davis, CA 95616.
  • | 11 J. D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

Abstract

Objective—To determine morphological and mechanical properties of trabecular bone of horses with a bone fragility syndrome (BFS; including silicate-associated osteoporosis).

Sample—Cylindrical trabecular bone samples from the distal aspects of cadaveric third metacarpal bones of 39 horses (19 horses with a BFS [BFS bone samples] and 20 horses without a BFS [control bone samples]).

Procedures—Bone samples were imaged via micro-CT for determination of bone volume fraction; apparent and mean mineralized bone densities; and trabecular number, thickness, and separation. Bone samples were compressed to failure for determination of apparent elastic modulus and stresses, strains, and strain energy densities for yield, ultimate, and failure loads. Effects of BFS and age of horses on variables were determined.

Results—BFS bone samples had 25% lower bone volume fraction, 28% lower apparent density, 18% lower trabecular number and thickness, and 16% greater trabecular separation versus control bone samples. The BFS bone samples had 22% lower apparent modulus and 32% to 33% lower stresses, 10% to 18% lower strains, and 41 % to 52% lower strain energy densities at yield, ultimate, and failure loads, compared with control bone samples. Differences between groups of bone samples were not detected for mean mineral density and trabecular anisotropy.

Conclusions and Clinical Relevance—Results suggested that horses with a BFS had osteopenia and compromised trabecular bone function, consistent with bone deformation and pathological fractures that develop in affected horses. Effects of this BFS may be systemic, and bones other than those that are clinically affected had changes in morphological and mechanical properties.

Abstract

Objective—To determine morphological and mechanical properties of trabecular bone of horses with a bone fragility syndrome (BFS; including silicate-associated osteoporosis).

Sample—Cylindrical trabecular bone samples from the distal aspects of cadaveric third metacarpal bones of 39 horses (19 horses with a BFS [BFS bone samples] and 20 horses without a BFS [control bone samples]).

Procedures—Bone samples were imaged via micro-CT for determination of bone volume fraction; apparent and mean mineralized bone densities; and trabecular number, thickness, and separation. Bone samples were compressed to failure for determination of apparent elastic modulus and stresses, strains, and strain energy densities for yield, ultimate, and failure loads. Effects of BFS and age of horses on variables were determined.

Results—BFS bone samples had 25% lower bone volume fraction, 28% lower apparent density, 18% lower trabecular number and thickness, and 16% greater trabecular separation versus control bone samples. The BFS bone samples had 22% lower apparent modulus and 32% to 33% lower stresses, 10% to 18% lower strains, and 41 % to 52% lower strain energy densities at yield, ultimate, and failure loads, compared with control bone samples. Differences between groups of bone samples were not detected for mean mineral density and trabecular anisotropy.

Conclusions and Clinical Relevance—Results suggested that horses with a BFS had osteopenia and compromised trabecular bone function, consistent with bone deformation and pathological fractures that develop in affected horses. Effects of this BFS may be systemic, and bones other than those that are clinically affected had changes in morphological and mechanical properties.

Contributor Notes

This manuscript represents a portion of a thesis submitted by the first author to the University of California-Davis Department of Biomedical Engineering as partial fulfillment of the requirements for a Master of Science degree.

Supported by the Dolly Green Endowment, the Center for Equine Health, the State of California pari-mutuel fund, and contributions by private donors.

Presented as a poster presentation at the Biomechanical Engineering Conference, Palo Alto, Calif, May 2011.

The authors thank Dr. Neil Willits for statistical assistance.

Address correspondence to Dr. Stover (smstover@ucdavis.edu).